IDN domain name not allowed in /settings/admin/theming

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### Steps to reproduce
1. Go to /settings/admin/theming
2. Type / paste an IDN domain name into the Web link field (second from the top), like `https://www.приклад.com/`

### Expected behaviour
An IDN domain name should be accepted as the URL.

### Actual behaviour
Validation error reported:  `The given web address is not a valid URL`

Only punycode version can be used.

### Server configuration

**Operating system:** NixOS 21.05

**Web server:** Nginx

**Database:** PostgreSQL

**PHP version:** 7.4.16

**Nextcloud version:** 21.0.2

**Updated from an older Nextcloud/ownCloud or fresh install:** fresh install (may have been upgraded within 21.0.x)

**Where did you install Nextcloud from:** NixOS nextcloud module

**Signing status:**
<details>
<summary>Signing status</summary>
`No errors have been found.`
</details>

**List of activated apps:**
<details>
<summary>App list</summary>

```
If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your Nextcloud installation folder
```
```
Enabled:
  - accessibility: 1.7.0
  - activity: 2.14.3
  - calendar: 2.3.0
  - cloud_federation_api: 1.4.0
  - comments: 1.11.0
  - contactsinteraction: 1.2.0
  - dashboard: 7.1.0
  - dav: 1.17.1
  - federatedfilesharing: 1.11.0
  - federation: 1.11.0
  - files: 1.16.0
  - files_pdfviewer: 2.1.0
  - files_rightclick: 1.0.0
  - files_sharing: 1.13.1
  - files_trashbin: 1.11.0
  - files_versions: 1.14.0
  - files_videoplayer: 1.10.0
  - firstrunwizard: 2.10.0
  - forms: 2.2.4
  - logreader: 2.6.0
  - lookup_server_connector: 1.9.0
  - nextcloud_announcements: 1.10.0
  - notifications: 2.9.0
  - oauth2: 1.9.0
  - password_policy: 1.11.0
  - photos: 1.3.0
  - privacy: 1.5.0
  - provisioning_api: 1.11.0
  - recommendations: 1.0.0
  - serverinfo: 1.11.0
  - settings: 1.3.0
  - sharebymail: 1.11.0
  - support: 1.4.0
  - survey_client: 1.9.0
  - systemtags: 1.11.0
  - text: 3.2.0
  - theming: 1.12.0
  - twofactor_backupcodes: 1.10.0
  - updatenotification: 1.11.0
  - user_status: 1.1.1
  - viewer: 1.5.0
  - weather_status: 1.1.0
  - workflowengine: 2.3.0
Disabled:
  - admin_audit
  - encryption
  - files_external
  - user_ldap
```
</details>

**Nextcloud configuration:**
<details>
<summary>Config report</summary>
```
{
    "system": {
        "apps_paths": [
            {
                "path": "\/var\/lib\/nextcloud\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/lib\/nextcloud\/store-apps",
                "url": "\/store-apps",
                "writable": true
            }
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "skeletondirectory": "",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "log_type": "syslog",
        "log_level": "2",
        "overwriteprotocol": "https",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "version": "21.0.2.1",
        "overwrite.cli.url": "https:\/\/localhost",
        "dbport": "",
        "dbtableprefix": "oc_",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "komora.xn--w5d.cc"
        ]
    },
    "apps": {
        "accessibility": {
            "installed_version": "1.7.0",
            "types": "",
            "enabled": "yes"
        },
        "activity": {
            "installed_version": "2.14.3",
            "types": "filesystem",
            "enabled": "yes"
        },
        "backgroundjob": {
            "lastjob": "22"
        },
        "calendar": {
            "installed_version": "2.3.0",
            "types": "",
            "enabled": "yes"
        },
        "cloud_federation_api": {
            "installed_version": "1.4.0",
            "types": "filesystem",
            "enabled": "yes"
        },
        "comments": {
            "installed_version": "1.11.0",
            "types": "logging",
            "enabled": "yes"
        },
        "contactsinteraction": {
            "installed_version": "1.2.0",
            "types": "dav",
            "enabled": "yes"
        },
        "core": {
            "installedat": "1623920688.4333",
            "vendor": "nextcloud",
            "public_webdav": "dav\/appinfo\/v1\/publicwebdav.php",
            "public_files": "files_sharing\/public.php",
            "backgroundjobs_mode": "cron",
            "theming.variables": "1eb659e1fac83b3a44cf8ec0b059ef16",
            "lastcron": "1625909891",
            "lastupdateResult": "{\"version\":\"21.0.3.1\",\"versionstring\":\"Nextcloud 21.0.3\",\"url\":\"https:\\\/\\\/download.nextcloud.com\\\/server\\\/releases\\\/nextcloud-21.0.3.zip\",\"web\":\"https:\\\/\\\/docs.nextcloud.com\\\/server\\\/21\\\/admin_manual\\\/maintenance\\\/upgrade.html\",\"changes\":\"https:\\\/\\\/updates.nextcloud.com\\\/changelog_server\\\/?version=21.0.3\",\"autoupdater\":\"1\",\"eol\":\"0\"}",
            "lastupdatedat": "1625908991"
        },
        "dashboard": {
            "installed_version": "7.1.0",
            "types": "",
            "enabled": "yes"
        },
        "dav": {
            "installed_version": "1.17.1",
            "types": "filesystem",
            "enabled": "yes"
        },
        "federatedfilesharing": {
            "installed_version": "1.11.0",
            "types": "",
            "enabled": "yes"
        },
        "federation": {
            "installed_version": "1.11.0",
            "types": "authentication",
            "enabled": "yes"
        },
        "files": {
            "installed_version": "1.16.0",
            "types": "filesystem",
            "enabled": "yes"
        },
        "files_pdfviewer": {
            "installed_version": "2.1.0",
            "types": "",
            "enabled": "yes"
        },
        "files_rightclick": {
            "installed_version": "1.0.0",
            "types": "",
            "enabled": "yes"
        },
        "files_sharing": {
            "installed_version": "1.13.1",
            "types": "filesystem",
            "enabled": "yes"
        },
        "files_trashbin": {
            "installed_version": "1.11.0",
            "types": "filesystem,dav",
            "enabled": "yes"
        },
        "files_versions": {
            "installed_version": "1.14.0",
            "types": "filesystem,dav",
            "enabled": "yes"
        },
        "files_videoplayer": {
            "installed_version": "1.10.0",
            "types": "",
            "enabled": "yes"
        },
        "firstrunwizard": {
            "installed_version": "2.10.0",
            "types": "logging",
            "enabled": "yes"
        },
        "forms": {
            "installed_version": "2.2.4",
            "types": "",
            "enabled": "yes"
        },
        "logreader": {
            "installed_version": "2.6.0",
            "types": "",
            "enabled": "yes"
        },
        "lookup_server_connector": {
            "installed_version": "1.9.0",
            "types": "authentication",
            "enabled": "yes"
        },
        "nextcloud_announcements": {
            "installed_version": "1.10.0",
            "types": "logging",
            "enabled": "yes",
            "pub_date": "Thu, 24 Oct 2019 00:00:00 +0200"
        },
        "notifications": {
            "installed_version": "2.9.0",
            "types": "logging",
            "enabled": "yes"
        },
        "oauth2": {
            "installed_version": "1.9.0",
            "types": "authentication",
            "enabled": "yes"
        },
        "password_policy": {
            "installed_version": "1.11.0",
            "types": "authentication",
            "enabled": "yes"
        },
        "photos": {
            "installed_version": "1.3.0",
            "types": "",
            "enabled": "yes"
        },
        "privacy": {
            "installed_version": "1.5.0",
            "types": "",
            "enabled": "yes"
        },
        "provisioning_api": {
            "installed_version": "1.11.0",
            "types": "prevent_group_restriction",
            "enabled": "yes"
        },
        "recommendations": {
            "installed_version": "1.0.0",
            "types": "",
            "enabled": "yes"
        },
        "serverinfo": {
            "installed_version": "1.11.0",
            "types": "",
            "enabled": "yes",
            "cached_count_storages": "2",
            "cached_count_filecache": "1197"
        },
        "settings": {
            "installed_version": "1.3.0",
            "types": "",
            "enabled": "yes"
        },
        "sharebymail": {
            "installed_version": "1.11.0",
            "types": "filesystem",
            "enabled": "yes"
        },
        "support": {
            "installed_version": "1.4.0",
            "types": "session",
            "enabled": "yes"
        },
        "survey_client": {
            "installed_version": "1.9.0",
            "types": "",
            "enabled": "yes"
        },
        "systemtags": {
            "installed_version": "1.11.0",
            "types": "logging",
            "enabled": "yes"
        },
        "text": {
            "installed_version": "3.2.0",
            "types": "dav",
            "enabled": "yes"
        },
        "theming": {
            "installed_version": "1.12.0",
            "types": "logging",
            "enabled": "yes",
            "color": "#000000",
            "url": "***REMOVED SENSITIVE VALUE***",
            "name": "\u041a\u043e\u043c\u043e\u0440\u0430 \u223f und\u0337e\u0337l\u0337\u011b\u0337t\u0337e\u0337d\u0337",
            "slogan": "***REMOVED SENSITIVE VALUE***",
            "cachebuster": "6"
        },
        "twofactor_backupcodes": {
            "installed_version": "1.10.0",
            "types": "",
            "enabled": "yes"
        },
        "updatenotification": {
            "installed_version": "1.11.0",
            "types": "",
            "enabled": "yes",
            "update_check_errors": "0",
            "core": "21.0.3.1"
        },
        "user_status": {
            "installed_version": "1.1.1",
            "types": "",
            "enabled": "yes"
        },
        "viewer": {
            "installed_version": "1.5.0",
            "types": "",
            "enabled": "yes"
        },
        "weather_status": {
            "installed_version": "1.1.0",
            "types": "",
            "enabled": "yes"
        },
        "workflowengine": {
            "installed_version": "2.3.0",
            "types": "filesystem",
            "enabled": "yes"
        }
    }
}
```
</details>

**Are you using external storage, if yes which one:** no

**Are you using encryption:** no

**Are you using an external user-backend, if yes which one:** no


### Client configuration
**Browser:** Firefox

**Operating system:** Linux

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IDN domain name not allowed in /settings/admin/theming #27906

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Uh oh!

IDN domain name not allowed in /settings/admin/theming #27906

Description

How to use GitHub

Steps to reproduce

Expected behaviour

Actual behaviour

Server configuration

Client configuration

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions